//=============================================================================
//     _   _                               ____                _  _          
//    | | | |  __ _  _ __   _ __   _   _  / ___|  _ __   _ __ (_)| |_   ___ 
//    | |_| | / _` || '_ \ | '_ \ | | | | \___ \ | '_ \ | '__|| || __| / _ \
//    |  _  || (_| || |_) || |_) || |_| |  ___) || |_) || |   | || |_ |  __/
//    |_| |_| \__,_|| .__/ | .__/  \__, | |____/ | .__/ |_|   |_| \__| \___|
//                  |_|    |_|     |___/         |_|                         
//
//                     HappySprite - We make sprites happy
//
// Copyright (c) 2007 by Tank Monkey Games
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//=============================================================================

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Xna.Framework;

namespace HappySprite
{
    public class EventScheduler : GameComponent
    {
        class Event
        {
            public GenericEventHandler Callback;
            public TimeSpan Delay;
        }

        ObjectPool<Event> eventPool = new ObjectPool<Event>();
        List<Event> events = new List<Event>();
        List<Event> workingList = new List<Event>();

        public EventScheduler(Game game)
            : base(game)
        {
            game.Components.Add(this);
        }

        public override void Update(GameTime e)
        {
            // Copy events to a working list so that master list can be modified
            workingList.Clear();
            workingList.AddRange(events);

            // Update each event and fire if enough time has passed
            foreach (Event ev in workingList)
            {
                ev.Delay -= e.ElapsedGameTime;

                if (ev.Delay <= TimeSpan.Zero)
                {
                    Cancel(ev.Callback);
                    ev.Callback();
                }
            }
        }

        public void Schedule(float delayInSeconds, GenericEventHandler callback)
        {
            Schedule(TimeSpan.FromSeconds(delayInSeconds), callback);
        }

        public void Schedule(TimeSpan delay, GenericEventHandler callback)
        {
            // Check arguments
            if (callback == null) throw new ArgumentNullException("callback");
            if (delay < TimeSpan.Zero) delay = TimeSpan.Zero;

            Event ev = eventPool.Create();
            ev.Delay = delay;
            ev.Callback = callback;

            events.Add(ev);
        }

        public void Cancel(GenericEventHandler callback)
        {
            // Check arguments
            if (callback == null) throw new ArgumentNullException("callback");

            // Find the event and remove it
            foreach (Event ev in events)
            {
                if (ev.Callback == callback)
                {
                    events.Remove(ev);
                    eventPool.Recycle(ev);
                    return;
                }
            }
        }
    }
}
